The well-known DIMM (dual in-line memory module) board has been used for years, in various forms, to provide memory expansion. A typical DIMM includes a conventional PCB (printed circuit board) with memory devices and supporting digital logic devices mounted on both sides. The DIMM is typically mounted in the host computer system by inserting a contact-bearing edge of the DIMM into a card edge connector. Systems that employ DIMMs and other similar modules provide, however, very limited profile space for such devices. The limited profile space available has exacerbated the already rising thermal energy loading demands precipitated by increasing speeds and capacities of both memory and logic.
Circuit modules and, in particular, memory modules are configured in a variety of ways, both dimensionally and electrically. A few examples include, registered DIMMs, fully buffered DIMMs (FB-DIMM), SO-DIMMS, PCI DIMMS, or graphics modules that are similar to DIMMs and have on-board memory and graphics engines. Some of these variations can be combined. For example, a SO-DIMM can be configured in a fully buffered mode.
Typical module construction is premised on a circuit board substrate typically devised of the well-known FR4 or similar materials. “FR” means flame retardant and type “4” means woven glass reinforced epoxy resin. Such substrates are a staple of the electronics industry but fall somewhat short of the demands imposed by contemporary applications.
For example, when a DIMM is inserted in the edge connector socket in which they are typically employed in a wide variety of applications, the pressure employed for the insertion can sometimes flex the board and cause cracking of the on-board ICs or separation or reduced reliability for the joints between the ICs and the circuitry embedded in the board. Further, FR4 typically exhibits a low thermal conductivity, thus inducing heat accumulation in modules.
What is needed therefore, is a new method and system for management of thermal loading of modules.